Gary is right: I have a similar set up, not quite as wide as yours and a longer throw too, which might make a bit of difference.
I have an X35, Isco II lens and a 112" wide 2.35:1 tab tensioned electric screen. Throw distance is about 19' and viewing distance about 11-12'. Very little pincushion to speak of due to the long throw (projector is at minimum zoom for lens use.
I make use of the lens memory function too since my Isco II isn't a true CIH lens as it slightly magnifies the image height when in place. I have saved the in lens setting as 2.35:1 and also a 1.85:1 setting which slightly zooms the non lens image so it saves too much fiddling about if I change discs and there is an aspect ratio change: I leave the lens in place for menus and trailers on a 2.35:1 film, but remove it if the film is 1.85:1/1.78:1.
I've seen three JVC X55s and one other X35 apart from my own: IMHO my X35 looks sharper than the zoomed X55s/X35 I've seen which I think is very much down to me using no zoom in the projector for 2.35:1 (and only a touch of zoom for 1.85:1). You need a decent lens to achieve this so don't run away with the idea that any lens will give the same result as I get.
"Don't believe everything you read on the internet". William Shakespeare 1615